A number of devices have been invented which address the problem of spreading a rubber tire casing to facilitate inspection and repair. These devices have been designed to spread a conventional tire of the type in which a cord reinforcement is imbedded around its circumference. A tire having a circumferential cord can be partially reversed by gripping a portion of the bead and pulling downward until a part of the inner surface of the tire is exposed to make the inspection and repair easier. For example, Dettling U.S. Pat. No. 1,849,034 utilizes a jack mechanism with a convex upper portion which forces the tire upward by bearing against the tread while two hooks hold the beaded edges of the tire stationary in order to reverse the tire shape and expose the inner surface. In Weiver U.S. Pat. No. 1,753,035 the device operates in a similar manner excepting that the tire is held by a plate having rounded corners and utilizes two opposing hooks driven by a piston and cylinder operated by air pressure which pull the tire beads downward to reverse the tire over the plate.
In Hazard U.S. Pat. No. 1,878,515 a pair of hook arms are driven by a piston and cylinder operated by air or pressurized fluid which engage the beads of a tire and pull them laterally apart while the base is supported by an arc shaped plate. This urges the tire into an inside-out attitude to expose the inner surface. These devices work well enough with conventional tires having reinforcing cords running circumferentially in that no injury to the tire results. In contrast, tires which have reinforcing cords which run radially in their orientation cannot be reversed in the above manner without the potential of causing a structural failure of the tire.
The present invention provides the spreading function in a device which is greatly simplified from the previous devices and which does not reverse the tire casing but merely spreads it a predetermined amount below the separation point of the cords to avoid injury to the radial tire casing. In addition, the spreading mechanism is arranged such that the maximum mechanical advantage is obtained at the point of maximum tire spread where the maximum force is required. This permits the mechanism to be operated manually with a minimum of effort.